BIOB50H3 Lecture 9: BIOB50 Lecture 9
13 Feb 2017
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One or both species benefit and neither is harmed. Mutualism (+/+) mutually beneficial interaction b/w two individuals of a species. Commensalism (+/0) interactions b/w individuals where one benefits and the other is not benefitted or harmed. Symbiosis: individuals of the two species in close physical contact with each other ex. Pea aphids and their symbionts, bacteria in human gut, parasites with hosts. Growth, survival or reproduction of individuals of one or both species is increased by their interaction with the other species. In mutualism there can be a cost to a benefit ex. Supplying food to the partner reduces its opportunity for growth. Vascular plants form mycorrhizae, symbiotic assoc. b/w plant roots and fungi that are mutualistic. Many evolve from exploitation relationships: consumption or parasitism. Positive interactions can be obligate and coevolved or facultative and loosely structured. Obligate: neither can survive without the other & their interaction led to evolution of unique featrues to benefit the other species: ex.
